Method of annealing metal



June 15 1926. 1,589,013

H. 8. LEE

METHOD OF A NNEAL ING METAL Filed August 27. 1924 X uuwzqm (7E////\\\\W/\\\\' Z d Patented June 15, I926 UNITED STATES- PATENT OFFICE} HARRY S. LEE, OF PLYMOUTH MICHIGAN.

" METHOD on ANNEALING METAL.

Application filed August 27, 1924. Serial no. 734,404.

This invention relates to a method of selfannealing metals and is especially adapted for annealing grey iron castings made in permanent or cast iron moulds. To prevent castings from oxidizing and to prevent the formation of a scale thereon, it is necessary to prevent the casting from coming in contact with the atmosphere while the same is. cooling. This invention prevents the casting andthe oxygen in the atmosphere from comin into contact.

Castings which are made in permanent moulds are very often chilled. This chilling is caused by the metal of the casting con- 1 tacting with the gast iron of the mould and cooling more quickly at the surfacethan in the interior. This chilling changes the chemical structure of the outer surface of the casting, and the chilled portion of the casting becomes very, hard, and makes the machining of the casting difiicult.

f 7 Another disadvantage of a chilled casting is that it does not allow the metal to be relieved of internal strains sojthat' when the metal is machined to size it retains its .di

mensions and shape.

A feature of my process is the self-annealing of the casting by .its own heat. The casting is precipitated into the annealing I perature or just solidified and the heat of the casting itself is confined therein and per f forms the annealing operation. 7 To illustrate this method, I have chosen todiagrammatically illustrate a mechanism for performing the method, though the different ste s in the .method can obviously be performed by hand. I a

In the drawings: I Fig-1 isa diagrammatic view of a system. Fig. 2 is'an enlarged section through my annealing tank, showing how my annealing material entirel covers the castlng precipitated in the ta I The description of the apparatus is sima designates .an furnace which ma I la be used for melting t e metal, from whic the molten metal is poured into the moulds b, which are traveling on a continuous belt or conveyor 0, driven from any suitable source of power and hereshown as a motor M.

This conveyor will convey the moulded castings to a point remote from the furnace, and means may be provided for auto- -compound while-it is at the annealing tem:

matically ejecting the casting from the mould and precipitating the same into an annealing tank (1. Obviously, these moulds could be'opened manually and the casting -or 'infusorial earth. The characteristic of this kieselguhr is that it is a very efiicient 'heat insulator, and prevents the escape of the heat from the heated casting that is dropped therein to the outside atmosphere. This finely powdered kieselguhr is like dust and actsina way similar to quicksand. As the casting is. dropped into the bath of 79 kieselguhr it quickly sinks into the ground kleselguhr, the kieselguhr closing about the casting and effectively excluding the oxy en in the atmosphere from the casting. he kieselguhr beneath the casting is packed suffic1ently by the weight of the casting so as to provide a pad of kieselguhr of several inches in thickness. I may or may not use a little powdered fire clay. When using this finely powdered fire clay together with the kieselguhr, I preferably use a mixture of about 10% fire clay to 90% kieselguhr.

This kieselguhr possesses the characteristlC S Of preventing'the' heat of the casting rom escaping an as a result of my experiments I find that a heated casting that is im-' mersed in this materialand kept therein for 24 hours is still too hot to be handled by hand. The internal heat of the casting performs the annealin As a result, this annealing bath of kleselguhr forms a very good annealing material as it enables one to cool the casting very, very slowly and in addition efiectively prevents oxygen from coming in contact with the casting while so cooling in the rocess of self-annealing.

signature. Y

HARRY S. LEE.

have aflixed my 

